1. Technical Field
The present invention relates generally to wireless networks and in particular to authorization handshakes between client devices and access points of wireless networks. Still more particularly, the present invention relates to a method and system for reducing interference from transmissions on the airwaves of an authentication request from a client device that is not authorized to operate within the particular network frequency range.
2. Description of the Related Art
A typical cellular communications system includes a number of fixed base stations (also known as access stations) interconnected by a cable medium often referred to as a system backbone. Also included in many cellular communications systems are intermediate base stations which are not directly connected to the system backbone but otherwise perform many of the same functions as the fixed access points. Intermediate base stations, often referred to as wireless base stations, increase the area within which base stations connected to the system backbone can communicate with mobile devices.
Associated with each base station is a geographic cell. The cell is a geographic area in which an access point has sufficient signal strength to transmit data and receive data from a mobile device such as a data terminal or telephone with an acceptable error rate. Typically, base stations will be positioned along the backbones such that the combined cell area coverage from each base station provides full coverage of a geographic area.
Mobile devices such as telephones, pagers, personal digital assistants (PDA's), data terminals, etc., are designed to be carried throughout the system from cell to cell. Each mobile device is capable of communicating with the system backbone via wireless communication between the mobile device and a base station to which the mobile device is registered. As the mobile device roams from one cell to another, the mobile device will typically de-register with the base station of the previous cell and register with the base station associated with the new cell. In order to provide sufficient cell area coverage, base station (or the antennas associated with each base station) within the cellular communications systems typically are distributed at separate physical locations throughout an entire geographic area.
The IEEE 802.11 standard has been adopted for wireless local area networks (WLANs) and has gained acceptance among the industrial, scientific and medical communities. The IEEE 802.11 standard for WLANs is a standard for systems that operate in the 2,400 to 2,483.5 MHz industrial, scientific and medical (ISM) band. The ISM band is available worldwide and allows unlicensed operation of spread spectrum systems. The IEEE 802.11 RF transmissions use multiple signaling schemes (modulations) at different data rates to deliver a single data packet between wireless systems. The latest IEEE 802.11 wireless LAN uses a band of frequencies near 2.4 Ghz for direct sequence spread spectrum transmissions.
The primary type of WLAN currently in operation utilizes fixed network access points with which mobile terminals are able to communicate. The structure is very similar to present day cellular networks. IEEE 802.11 makes provisions for data rates of either 1 MBps, 2 Mbps, 5.5 Mbps, and 11 Mbps and calls for operation in the 2.4–2.4835 GHz frequency.
Wireless technology now reaches or is capable of reaching virtually every location on the face of the earth motivated in part by people's desire for increased mobility. Since wireless technology uses the air waves, frequencies are controlled by governmental regulatory bodies such as the FCC, CISPR, etc. These bodies have the responsibilities to approve frequency ranges and power levels for various products (i.e., providing homologation approval). Thus, a client device may be legal (i.e., supported within the approved frequency range) in one country and illegal (i.e., not supported within the approved frequency range) in another country. This information is important due to the relative ease with which the device may be activated in a country in which it is illegal. Operating the illegal device results in the device interfering with other devices operating within a particular country by promulgating signals that are not supported for that type of device and which may be utilized for other types of communication.
A fundamental problem with wireless technology is the handshake between the client device and the access point. Currently, client devices constantly search for an access point within range. In areas such as Europe and Latin America, where an individual may travel across country borders relatively frequently/easily, a device may be constantly transmitting a request for a handshake within a network located in another country that does not support that device. Since the legality of the device is based on homologation approval, the user merely assumes the device is not in range of an access point and does not consider the havoc being wreaked on the airwaves due to the constant transmissions of his device.
The present invention recognizes that it would be desirable to provide a method and system within a wireless network that switches the authorization negotiating scheme from the client devices to the access points to prevent a client device from continually broadcasting in countries in which it is not approved. A method and system that changes the discovery mechanism between access point and client device of the 802.11 protocol while reducing the amount of unapproved transmission outside of the homologated frequencies would be a welcomed improvement. It would be further desirable to provide both an access device and a client device that operated according to the new discovery mechanism. These and other benefits are provided by the invention as described herein.